Screen Command

SSH is great for accessing my home FreeBSD server. Unfortunately, sometimes an install takes too long and I need to disconnect from the session without stopping the current process. Screen to the rescue. First, install it from the ports collection.

#cd /usr/ports/sysutils/screen
#make install clean

Next, execute the screen command. This will create and attach to a new screen session with a single window. To list all screen sessions use the screen command with the “-ls” option. To reattach to one of those listed sessions use the “-r session_name” parameter.

While attached to a screen session, commands can be sent to the screen instead of the window shell by typing ctrl + a followed by the command key. Here is the help displayed using ‘?’.

                       Screen key bindings, page 1 of 2.

                       Command key:  ^A   Literal ^A:  a

  break       ^B b         license     ,            removebuf   =
  clear       C            lockscreen  ^X x         reset       Z
  colon       :            log         H            screen      ^C c
  copy        ^[ [         login       L            select      '
  detach      ^D d         meta        a            silence     _
  digraph     ^V           monitor     M            split       S
  displays    *            next        ^@ ^N sp n   suspend     ^Z z
  dumptermcap .            number      N            time        ^T t
  fit         F            only        Q            title       A
  flow        ^F f         other       ^A           vbell       ^G
  focus       ^I           pow_break   B            version     v
  hardcopy    h            pow_detach  D            width       W
  help        ?            prev        ^H ^P p ^?   windows     ^W w
  history     { }          quit                    wrap        ^R r
  info        i            readbuf     <            writebuf    >
  kill        K k          redisplay   ^L l         xoff        ^S s
  lastmsg     ^M m         remove      X            xon         ^Q q

                  [Press Space for next page; Return to end.]

The basic key commands to needed by a beginner are ‘c’ (create window), ‘n’ (next window), ‘p’ (previous window), ‘k’ (kill window), ‘w’ (window list), ‘?’ (help), and ‘d’ (detach from session).

So give screen a try and explore the other features like logging and monitor.


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